This invention is related generally to mail handling apparatus and particularly to such apparatus which applies pre-addressed labels to mailing pieces.
At the present time, the United States Postal Service requires that large users of mail package their mailing pieces according to zip codes to facilitate mail delivery. Accordingly, large mail order houses and the like which address their mailing pieces by applying thereto a pre-addressed label require that the labels be grouped according to zip codes. Typically, the labels are provided in a sheet on which labels bearing the same zip code are arranged together, with the first label of a new zip code group bearing an asterisk or other indicia indicative of a new zip code.
In applying the labels to mailing pieces, a sheet of labels is fed to a label head under which a conveyor moves the mailing pieces. The label head applies the labels to the mailing pieces which are then further conveyed to a mail handling station where the addressed mailing pieces are bundled according to zip codes.
To facilitate such bundling, prior label heads have included a sensor for detecting the asterisk or other indicia indicating a new zip code. The sensor in turn actuates a kicker or the like disposed downstream from the label head for skewing the mailing piece which bears the label on which the asterisk was sensed. An operator is thus provided with a visual indication that a new zip code group of mailing pieces is being conveyed.
Frequently, however, the bundling station may be located remotely from the label head, thereby making it impractical to activate a kicker located near the bundling station. Under these circumstances, it has been proposed that the asterisk sensor activate a coating device for coating the label bearing an asterisk with a radiation-emissive substance. The mailing pieces may then be carried or conveyed to the remote bundling station where a radiation detector will sense the presence of a coated label and, in response thereto, actuate a nearby kicker.
A problem which may arise with the latter arrangement is that the label material and/or the mailing piece to which a label is applied may have been previously treated during its manufacture with a dye which is radiation-emissive. As a result, the radiation detector is unable to reliably differentiate between mailing pieces bearing labels which were coated by the coating device and other labels. Consequently, the kicker may be actuated to skew the wrong mailing pieces.
An additional problem associated with mail handling apparatus using coating devices is that the substance issued by the coating device may not always be accurately deposited on a label when the speed of the conveyor which conveys the mailing pieces is varied. The subsequent detection of a label bearing the deposited substance is, therefore, made more difficult. These and other problems associated with some prior mail handling apparatus have resulted in less than optimum sorting of mailing pieces.
Accordingly, it is an object of this invention to provide an improved mail sorting system which overcomes the deficiencies associated with prior systems.
It is a more specific object of this invention to provide a mail sorting system wherein a radiation-emissive substance is more accurately coated on selected address labels and wherein the coated labels are reliably distinguished from non-coated labels.